Oracle SQL_TRACE使用小结

一、关于基础表
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rd-A6z/&[1R1] H680758 Oracle10G之前，启用AUTOTRACE功能需要手工创建plan_table表，创建脚本为$ORACLE_HOME/rdbms/admin /utlxplan.sql。但在10g中，已经默认创建了PLAN_TABLE$的基表，并以public用户创建了相应的同义词PUBLIC。ITPUB个人空间DR#IlHrT
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SQL> select owner,object_name,OBJECT_TYPE from dba_objects where object_name like '%PLAN_TABLE%';

OWNER                          OBJECT_NAME          OBJECT_TYPE
------------------------------ -------------------- -------------------
SYS                            SQL_PLAN_TABLE_TYPE  TYPE
PUBLIC                         SQL_PLAN_TABLE_TYPE  SYNONYM
SYS                            PLAN_TABLE$          TABLE
PUBLIC                         PLAN_TABLE           SYNONYM
EXFSYS                         EXF$PLAN_TABLE       TABLE

SQL> select * from dba_synonyms where SYNONYM_NAME like '%PLAN_TABLE%';
 
OWNER          SYNONYM_NAME           TABLE_OWNER                    TABLE_NAME                     DB_LINK
-------------- ---------------------- ------------------------------ ------------------------------ --------
PUBLIC         SQL_PLAN_TABLE_TYPE    SYS                            SQL_PLAN_TABLE_TYPE
PUBLIC         PLAN_TABLE             SYS                            PLAN_TABLE$ ITPUB个人空间SHlU.AC*Q.O

i5G1_]E7r680758 从上面的结果可以看出，PLAN_TABLE正是基于PLAN_TABLE$的同义词。
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二、关于plustrace角色ITPUB个人空间,@/SkvSq/
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和Oracle9i一样，10g中plustrace角色默认也是disabled的。如果使用非授权用户打开Oracle trace功能会得到以下的错误。
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SQL> conn hr/hr
Connected.
SQL> set autotrace trace
SP2-0618: Cannot find the Session Identifier.  Check PLUSTRACE role is enabled
SP2-0611: Error enabling STATISTICS report
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这时需要执行$ORACLE_HOME/sqlplus/admin/plustrce.sql脚本，手工创建plustrace角色。
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npN8MRyT6fs680758 SQL> @$ORACLE_HOME/sqlplus/admin/plustrce.sql;
SQL>
SQL> drop role plustrace;
drop role plustrace
          *
ERROR at line 1:
ORA-01919: role 'PLUSTRACE' does not exist

SQL> create role plustrace;

Role created.

SQL> grant select on v_$sesstat to plustrace;
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Grant succeeded.

SQL> grant select on v_$statname to plustrace;

Grant succeeded.

SQL> grant select on v_$mystat to plustrace;

Grant succeeded.

SQL> grant plustrace to dba with admin option;

Grant succeeded.

SQL> set echo off
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接下来就可以手工将plustrace角色授予需要的角色或用户，或者直接将其授予public角色，这样所有public角色的用户都有使用autotrace功能的权限了。
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}tW0?+n`&F Ta680758 SQL> grant plustrace to hr;

Grant succeeded.

SQL> conn hr/hr
Connected.
SQL> set autotrace trace
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三、关于autotrace功能内部操作ITPUB个人空间 H s^*w_U
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默认的，在启用autotrace功能时Oracle另启用一个session，专门用于收集和输出统计信息。
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SQL> set autotrace off
SQL> select sid,serial#,username from v$session where username is not null;

SID    SERIAL# USERNAME
---------- ---------- ------------------------------
       146        906 SYS
       159          3 SYS
......
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SQL> set autotrace on exp
SQL> select sid,serial#,username from v$session where username is not null;

SID    SERIAL# USERNAME
---------- ---------- ------------------------------
       129          6 SYSMAN
       135          4 DBSNMP
       136        356 SYSMAN
       143         45 SYSMAN
       145         10 SYSMAN
       146        906 SYS
       149         38 DBSNMP
       159          3 SYS

8 rows selected.
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Execution Plan
----------------------------------------------------------
Plan hash value: 3733760267

--------------------------------------------------------------------------------------------
| Id  | Operation                | Name            | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT         |                 |     1 |   108 |     0   (0)| 00:00:01 |
|   1 |  NESTED LOOPS            |                 |     1 |   108 |     0   (0)| 00:00:01 |
|*  2 |   FIXED TABLE FULL       | X$KSUSE         |     1 |    95 |     0   (0)| 00:00:01 |
|*  3 |   FIXED TABLE FIXED INDEX| X$KSLED (ind:2) |     1 |    13 |     0   (0)| 00:00:01 |
--------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

2 - filter("S"."KSUUDLNA" IS NOT NULL AND "S"."INST_ID"=USERENV('INSTANCE') AND
              BITAND("S"."KSSPAFLG",1)<>0 AND BITAND("S"."KSUSEFLG",1)<>0)
   3 - filter("S"."KSUSEOPC"="E"."INDX")
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而收集统计信息的时候，则多出一个session。ITPUB个人空间y s:~'f%N!t/_

SQL> set autotrace on stat
SQL> select sid,serial#,username from v$session where username is not null;

SID    SERIAL# USERNAME
---------- ---------- ------------------------------
       126        692 SYS
       129          6 SYSMAN
       135          4 DBSNMP
       136        356 SYSMAN
       143         45 SYSMAN
       145         10 SYSMAN
       146        906 SYS
       149         38 DBSNMP
       159          3 SYS ITPUB个人空间,K,`0IG|7/g`2H

9 rows selected.

Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
          0  consistent gets
          0  physical reads
          0  redo size
        695  bytes sent via SQL*Net to client
        385  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          9  rows processed
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"S7k;D x8x@X5D680758 SQL> select a.sid,a.serial#,a.username,b.pid,b.spid
  2  from v$session a,v$process b
  3  where a.paddr=b.addr and a.username is not null;

SID    SERIAL# USERNAME                              PID SPID
---------- ---------- ------------------------------ ---------- ------------
       159          3 SYS                                    15 4261
       146        906 SYS                                    18 6977
       126        692 SYS                                    18 6977
......

9 rows selected.

$ ps -ef|grep -v grep|grep 6977
oracle    6977  6976  0 21:22 ?        00:00:00 oraclerandy (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq))) ITPUB个人空间*a*/.~de6b

%Q)F:UNrB680758 四、关于DBMS_SYSTEM.SET_SQL_TRACE_IN_SESSIONITPUB个人空间?'j8P MhQ4[|L^
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其实我们更多的时候需要跟踪的其他用户的进程，而很多这样的用户可能没有被授予或者不允许授予plustrace角色。这时可以使用 DBMS_SYSTEM.SET_SQL_TRACE_IN_SESSION过程来实现对进程的跟踪，该过程需要提供用户进程的sid和serial#。ITPUB个人空间O*M7? xK4D�z
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SQL> select sid,serial#  from v$session where username ='HR';

SID    SERIAL#
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       159          5

SQL> exec dbms_system.SET_SQL_TRACE_IN_SESSION(159,5,true);

PL/SQL procedure successfully completed.

SQL> select a.sid,a.serial#,a.username,b.pid,b.spid
  2  from v$session a,v$process b
  3  where a.paddr=b.addr and a.username='HR';

SID    SERIAL# USERNAME                              PID SPID
---------- ---------- ------------------------------ ---------- ------------
       159          5 HR                                     15 9080
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回到用户HR的连接中执行SQL语句，然后使用tkprof工具格式化USER_DUMP_FILE目录中的跟踪文件。
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X'F%jE5@1W680758 $ tkprof randy_ora_9080.trc 9080.txt
$ more 9080.txt

......
select *
from
 jobs

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call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        2      0.01       0.02          0          0          0           0
Execute      2      0.00       0.00          0          0          0           0
Fetch        6      0.00       0.04          6         18          0          38
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total       10      0.02       0.06          6         18          0          38

Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 55

Rows     Row Source Operation
-------  ---------------------------------------------------
     19  TABLE ACCESS FULL JOBS (cr=9 pr=6 pw=0 time=42771 us)
......
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从跟踪文件中，可以发现很多关于Oracle在实现用户需求时的内部操作，深入研究确实会有很多的收获。不过这里我们关心的是上面摘录的部分，可以看到select * from jobs执行计划和相关的统计信息。
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五、使用会话级10046事件ITPUB个人空间i/-{{'D4?u

,t }a#r#IX Q`4T8wV680758 除了上述的方法外，还可以使用会话级的10046事件来实现进程跟踪。
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SQL> alter session set events '10046 trace name context forever, level 12';

SQL> alter session set events '10046 trace name context off';
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8A!Q'R.@�R(yY680758 如果用户没有alter session的权限，可以使用DBMS_SYSTEM.SET_EV过程来实现对用户进程的跟踪。
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SQL> desc DBMS_SYSTEM

......
PROCEDURE SET_EV
 Argument Name                  Type                    In/Out Default?
 ------------------------------ ----------------------- ------ --------
 SI                             BINARY_INTEGER          IN
 SE                             BINARY_INTEGER          IN
 EV                             BINARY_INTEGER          IN
 LE                             BINARY_INTEGER          IN
 NM                             VARCHAR2                IN
......

几个参数分别是进程sid，serial#，event name，level，username。 ITPUB个人空间3uAU+_`;P0X:M

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